1. Technical Field
The present invention generally relates to a superchaged engine and more particularly relates to an engine associated with a turbocharger, a large capacity air compressor for a brake and a small capacity air compressor for supercharging.
2. Background Art
In automobile engineering, one primary object is to attain an engine which is lightweight, compact but with high output and less fuel consumption. Also, an increasing degree of freedom in various aspects in an engine-designing is an important goal. For these reasons, the engine has been supercharged. In other words, research on high net mean effective pressure has been conducted. However, following problems are not solved yet:
(i) The engine torque becomes lower at low speed conditions as compared with an engine output having a same output; and PA1 (ii) Engine brake force and exhaust brake force do not change with output of the engine so that these brake forces decrease relatively.
The present assignee filed several Japanese patent applications, for example "Turbine-type brake" Japanese Patent Application No. 63-302151. These applications disclose an arrangement represented by an illustration of FIG. 3 of the accompanying drawings. Specifically, a centrifugal compressor (b) is connected with a crankshaft (a) via a gear train (d) and the compressor (b) is operated during a braking operation to apply a brake force to the crankshaft (a) or an engine (c). This arrangement can overcome the above-mentioned problem (ii) but cannot overcome problem (i).